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GST Calculator – Add or Remove GST, CGST, SGST & IGST

Add GST to a price or take it out of a GST-inclusive amount, and see the CGST + SGST or IGST split for any rate. Free, private and works on your phone.

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How to use the GST calculator

  1. Choose Add GST if your amount does not include GST yet, or Remove GST if it already includes GST.
  2. Enter the amount in rupees.
  3. Tap a GST rate (5%, 18% or 40% cover most items) or type any other rate.
  4. Choose Within state for CGST + SGST, or Other state for IGST.
  5. Read the amount before GST, the GST, the total and the tax split. Tap Copy to paste the breakdown into a message or invoice.

How GST is calculated

Adding GST to a price that does not include tax:

GST = Amount × Rate ÷ 100   ·   Total = Amount + GST

Removing GST from an amount that already includes tax:

Price before GST = Amount × 100 ÷ (100 + Rate)   ·   GST = Amount − Price before GST

Example: adding 18% GST

A service costs ₹10,000 before tax and the GST rate is 18%.

  • GST = 10,000 × 18 ÷ 100 = ₹1,800
  • Total = 10,000 + 1,800 = ₹11,800
  • Within the same state: CGST ₹900 + SGST ₹900. To another state: IGST ₹1,800.

Example: removing GST from an MRP

A product costs ₹11,800 including 18% GST.

  • Price before GST = 11,800 × 100 ÷ 118 = ₹10,000
  • GST included = 11,800 − 10,000 = ₹1,800

A common mistake is to subtract 18% of ₹11,800 (₹2,124). That is wrong, because the 18% was charged on ₹10,000, not on ₹11,800.

GST rates after the 2025 changes

From 22 September 2025, GST was simplified. Most items now attract 5% or 18%, a 40% rate applies to specified luxury and sin goods, and a few special rates remain (for example 3% on gold and 0.25% on rough diamonds). The old 12% and 28% slabs now apply to very few items, but you may still need them when checking older bills. The rate for any item depends on its HSN or SAC code — confirm it on the official CBIC rate list before invoicing.

Who uses a GST calculator

  • Shop owners and small businesses preparing quotes and invoices.
  • Freelancers and consultants adding 18% GST to their fees.
  • Buyers checking how much of an MRP is tax.
  • Accounts staff splitting tax into CGST, SGST and IGST for returns.

Working out a discount first? Use the discount calculator, then add GST here. To write the invoice total in words, use number to words.

Frequently asked questions

How do I add GST to a price?

Multiply the price by the GST rate and divide by 100, then add it to the price. For ₹10,000 at 18%, GST is ₹1,800 and the total is ₹11,800.

How do I remove GST from a GST-inclusive amount?

Divide the amount by (100 + GST rate) and multiply by 100 to get the price before GST. For ₹11,800 at 18%: 11,800 × 100 ÷ 118 = ₹10,000, so the GST included is ₹1,800. Do not simply subtract 18% of ₹11,800 — that gives the wrong answer.

When is GST split into CGST and SGST?

When the seller and the buyer are in the same state (an intra-state supply), GST is charged as half Central GST and half State GST (or Union Territory GST). For 18%, that is 9% CGST + 9% SGST.

When is IGST charged?

IGST (Integrated GST) applies when goods or services go from one state to another (an inter-state supply), and on imports. The full rate is charged as IGST — for example 18% IGST instead of 9% + 9%.

What are the GST rates now?

Since 22 September 2025 most goods and services fall under two main rates, 5% and 18%, with 40% for specified luxury and sin goods and a few special rates such as 3% on gold. Rates are set per item (HSN/SAC code), so always confirm the rate for your product on the official CBIC rate list.

Why do CGST and SGST sometimes differ by one paisa?

When the total GST has an odd number of paise, it cannot be split exactly in half. The calculator rounds CGST to the nearest paisa and gives SGST the remainder, so the two always add up to the exact GST.

Can I use this for my GST invoice?

Yes, for working out the amounts. Your invoice must also show details such as your GSTIN, the HSN/SAC code, the place of supply and the invoice number. Check with your accountant if you are unsure.

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